Heating system and low draft loss dust collector for use therein



H. L. WAGNER HEATING SYSTEM AND LOW DRAFT LOSS DUST COLLECTOR FOR USE THEREIN May 4, 1954 2 Sheets-Sheet 1 Filed Aug. 22, 1950 m m m m May 4, 1954 H. WAGNER HEATING SYSTEM AND LOW DRAFT LOSS DUST COLLECTOR FOR USE THEREIN 2 Sheets-Sheet 2 Filed Aug. 22 1950 O0 OOOOOOOOOOQOOOOOOOO r 5 W H N Y w E 4 r V W a w r n M a Z A //h/fi Wm 7 I r 1 /I I My z 9 2 l M l a 2 m 2 Patented May 4, 1954 HEA'EKNG SYSTEM AND LOW DRAFT LOSS DUST COLLECTOR FOR USE THEREIN Herbert L. Wagner, Detroit, Mich, assignor to Detroit Stoker Company, Detroit, Mich, a corporation of Michigan Application August 22, 1950, Serial No. 180,795

(Cl. l8375) 4.- Claims.

turbines and the like, by the circulation of heated gases which rise from a coal bed or the like and circulate around a boiler. These gases contain dust or particles, some of which may be high in carbon and reusable, and the particles are removed. from the gases before they pass out into the atmosphere, or the like. In the past, a dust collector has been employed for this purpose, and in order to efficiently remove all of the particles the collector has been of the type which utilizes centrifugal force to separate the solid particles from the gases, and as a result there is a large draft loss in the system and a large fan, or the like, must be employed to pull the gases through the dust collector and system, .which necessitates relatively large power consumption.

The solid particles so collected in the dust ,collector are either discarded in the ash handling system or are all recirculated and returned to the fuel bed. As the large particles have ahigh carbon content and can be reburned in the fur nace, they are wasted if they are discarded with the noncombustible particles in the gases. The small or fine particles are, however, primarily ash, and if they are recirculated the ash con centration in the system becomes high and leads to unsatisfactory results. Therefore, a more efficient system would be provided if the large particles, high in combustible material, were separated from the fine particles, low in combustible material, so that the large particles could be reburned, without at the same time requiring a great deal more power to pull the gases through the system.

It is, therefore, an object of this invention to provide apparatus for separating or removing solid particles from the gases, which apparatus is so designed and constructed that the larger particles, which are high in carbon content, are separated from the gases in a low draft loss dust collector and are subsequently returned to the coal bed for reburning, while the smaller particles, high in non-combustible material, are separated from the gases in a second dust collector, from which they can be discarded.

'It is a still further object of this invention to provide apparatus of the aforementioned type, in which the pressure drop or draft loss in the large particle dust collector is comparatively small so that the use of an excessive amount of power in order to pull the gases through the dust collectors is not necessary. I

It is a still further object of this invention .to provide in a low draft loss dust collector of the aforementioned type, a novel arrangement for causing the gases and gas borne particles to flow in a predetermined path, such that the particles can and will be removed from the gases and deposited in a hopper. or the like for subsequent reburning.

It is a still further object of this invention to provide apparatus of the aforementioned type which is relatively inexpensive to manufacture, simple in constructionand efiicient in operation.

These and other objects of. this invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, in which:

Figure l is a side view, partially in section and partially in elevation, of a furnace and steam generating mechanism with the dust collector apparatus of this invention associated therewith.

Fig. 2 is an enlarged fragmentary sectional view of a low draft loss dust collector, illustrating a further embodiment of the invention;

Fig. 3 is a view similar to Fig. 2, illustrating a still further embodiment of the invention;

Fig. 4 is a view similar to Fig. 3, illustrating a still further embodiment of the invention;

Fig. 5 is a view similar to Figs. 2-4 and illustrating a still further embodiment of the invention;

Fig. 6 is a view similar to Figs. 2-5, illustrating a still further embodiment of the invention; and

Fig. 7 is a sectional view of the structure illustrated in Fig. 6, taken along the line 'i-l thereof.

Referring now to the drawings and more particularly to Fig. 1, it will be seen that a furnace 9 is provided, having a stoker Ii therein, which includes the usual apparatus it, for supplying coal to a movable grate l5, on which the coal is burned. Air is supplied to aid in the burning of the coal, through suitable blower apparatus H. The gas due to the burning of coal on the grate it, flows upwardly in the furnace and a suitable boiler I9 is provided in the upper portion of the furnace, in which water is heated to steam. The boiler includes a plurality of coils or tubes and. a super heater through which the water is circulated and heated to steam. The steam generated in the boiler flows out through a suitable conduit 2| to a steam operated turbine, or the like, for generating power.

The gases flowing through the furnace and past the boiler tubes flow downwardly into a breeching or a conduit 23, which, as illustrated in Fig. 1, is connected with the furnace adjacent the boiler tubes. The gases flowing through the furnace carry solid particles, some of which will be relatively large and others of which will be relatively small. The large particles are generally high in carbon content and are such as can be reburned in the furnace, while the small particles are low in carbon content and are primarily ash. The conduit or breeching 23 has one or more hoppers 25 connected with the underside thereof and extending throughout the length thereof. The conduit 23 also has an opening 2! in the side or outer wall 28 thereof, which extends laterally or horizontally and communicates with a dust collector 29, of any suitable type, which is adapted to efficiently remove all the particles from gases flowing upwardly therefrom through a suitable heat exchanger 3!, which is connected in the system in a conventional and suitable manner. The collector 29 is generally of the type which is constructed to separate gas borne particles from the gases by centrifugal force and so is of the high draft loss or high pressure drop type. A suitable fan, or the like, may be connected with the upper end of the heat exchanger to pull the gases out through the system. The breeching or conduit 23 is constructed as will hereinafter apear, to form a low draft loss dust collector for removing the large, high carbon content particles from the gases, while the dust collector 29 removes the small particles from the gases and deposits them in hoppers 33, from which they can be removed by a suitable ash handling operation.

In order to remove the large particles from the gases in the low draft loss dust collector, without a large draft loss or pressure drop, the conduit 23 has a baiile member 35 therein extending angularly inwardly and downwardly from the side wall 28 thereof adjacent to and above the opening 21. Therefore, gases flowing downwardly into the conduit 23 from the furnace will be defiected by the bafi'le 35 toward the opposite wall 39 of the conduit 23, and will make a turn of approximately 180 .in order to flow out through the opening 21. The gases cannot pass through hopper 25 so the only path of flow is through opening 27, and the bafiie 35 makes the gases and gas borne particles turn more than 90 in order to flow out through the opening. A second baifie ii projects from the wall 28 of the conduit 23 adjacent to the lower edge of .the opening 21', so as to be in the path of flow of the gases as they flow toward the opening 27. The bafile 4! acts in effect as a skimmer, to engage the larger.particles and deflect the same downwardly into the hopper 25. The baffle M is not, however, effective to separate the small particles from the gases and these particles will flow with the gases out through the opening 21. The large particles which fall into the hopper or hoppers 25 will'be removed therefrom and blown back onto the stoker grate I 5 by means of air flowing under pressure through a conduit 43, and through a conduit 45 on the lower end of the hopper 25, 2'

so that the particles wil be picked up in the air stream and will pass with the air stream through the conduit 43 and back into the furnace for reburning.

Thus, the gases flowing vertically down into the conduit 23 will turn more than to pass through the opening 21, due to the baffle 35, and will turn approximately so that the larger particles will either fall by gravity into the hoppers 25, or will be deflected by the skimmer baille ll into the hopper 25 for return to the stoker. It can be readily appreciated that there will be a very small pressure drop or draft loss in the dust collector formed in the conduit 23, and it will also be appreciated that while the dust collector 29 may be a relatively high draft loss collector, in order to be exceptionally efficient to remove all of the small particles from the gases, the low draft loss collector does not add materially to the power needed to pull the gases through the heat exchanger 31. Thus, the apparatus illustrated elfectively separates the large particles from the gases for reburning in the furnace, without adding appreciably to the power consumption needed to pull the gases through the system, and the second dust collector 29 cffectively removes all of the remaining particles from the gases, so that they can be handled in a suitable ash handling system. Thus, a more efiicient operating unit is provided, in which coal consumption is at a minimum and in which power consumption is not adversely afi'ected.

The low draft loss dust collector is shown in Fig. 1 as being disposed ahead of the high draft loss dust collector 29, and the heat exchanger 3|, as well as in the breaching below the furnace and boiler. The collector, however, could be provided and formed in any gas duct and so arranged that the gas borne particles of solid material will be thrown out of the gas stream and into a hopper for return to the stoker.

The embodiment of the invention illustrated in Fig. 2 is quite similar to that illustrated in Fig. 1, in that the gases flow vertically down through the conduit 23 and the baffle 35' is provided to cause the gases to make more than a 90 turn as they pass vertically through the conduit 23 and out through the horizontal opening 21. In this embodiment, the skimmer baffle ll is also provided for causing the solid particles to be deposited in the hopper 25'. In addition to the bafiles 35 and 4| an additional skimmer bafile 4'! is attached to the baflle 35 at the upper or upstream end thereof, and this skimmer 41 skims off the gas borne particles as they concentrate on or engage the top of the baffle 35 and causes the particles to drop down through a tube M which is connected with skimmer 4'5 and has its lower end disposed in the hopper 25, so as to convey the solid particles to the hopper. With this arrangement solid particles engaging or concentrating on the baiiie 35 will be conveyed to the hopper 25' through the tube '49, and the baffles 35' and 4| act in the same manner as previously described, to cause the gases to turn more than 90 before passing through the opening 2'! so that the large particles will be separated from the gases. Thus, in this embodiment, an additional skimmer is provided to aid in separating the particles from the gas.

In the embodiment of the invention illustrated in Fig. 3, the construction of the low draft dust collector is quite similar to that previously described. However, in this embodiment a bafile 5| is connected with the wall 39 of the conduit 23 and is disposed above the baffle 35 so as to positively force the gases adjacent the wall 39 into engagement with the baflle 35" so as to cause the particles to engage the top side of baffle 35'. The bafile 35" acts as previously described to cause the gases and particles to flow again toward the wall 39". A plurality of verticall; spaced skimmer baffles 53 are disposed adjacent to but spaced from the conduit wall 39, and these baffles 53 intercept the gas borne particles as the gas is deflected toward wall 39" as a result of engagement with the bafiie 35". The gas borne particles intercepted by bafiies 53 will drop where the particles will be skimmed by bafiie 41a and pass through tube i800 to the hopper a. Any gas borne particles which pass over the top of the skimmer 41a will engage the wall 38a and turn to come up toward the opening 210, so that they will be skimmed by the baffle lla and dropped into the hopper 25a in the same manner as previously described.

In the embodiment of the invention illustrated in Fig. 5, the gases from the furnace or boiler outlet flow through a horizontal conduit portion 55, which terminates in the conduit portion 23b, comparable to that previously described. The baiile b is disposed above the opening Zlb in the same manner as previously described, so as to cause the gas to turn substantially 180 in order to pass from the conduit 23b through the opening 2%. The baffle lib is provided adja cent the lower side of the opening 211) so as to skim off large particles and drop them in the hopper 25b, in the manner previously described. The gases passing through the opening 2Tb will flow downwardly through an air heater or heat exchanger Slb, into conduit 23c adjacent the lower end thereof. Baiiies 35c and Me are provided adjacent a horizontally extending opening 210, in the conduit in substantially the same manner as previously described. A hopper 250 is disposed below the bafile Me, and the baffle 350 will cause the gases and gas borne particles to turn approximately 180 to pass through the opening 270 and the baiiie ilo will skim off any particles which were not removed in the upper dust collector and drop them into the hopper 25c, in the same manner as previously described. In this embodiment, two low draft loss dust collectors are employed, one ahead of the heat exchanger and the other at the outlet of the heat exchanger, and ahead of the high draft loss dust collector which separates the small particles from the gas prior to the passage of the gases into the atmosphere or the like.

In the embodiments illustrated in Figs. 6 and '7, the construction of the low draftloss dust collector is identical to that described in connection with Fig. 1, except that the low draft loss dust collector is disposed below the heat exchanger Sld. Thus, the gases flowing downwardly through the heat exchanger Sid are deflected by the baffle 3511 so as to make a substantially 180 turn and the gas borne particles will be skimmed from the gases by the skimmer baffle did, so as to fall into the hoppers 25d, while the gases will pass outwardly through the opening 2101 into the atmosphere, or a subsequent dust collector.

Figs. 6 and 7 show the manner in which the several hoppers 25d are provided throughout the length of the conduit 23d, and also illustrate the manner in which the baiiies 4 id and 35d are supported by the breeching structure through the use of suitable braces 59 and by being connected directly to the wall 28d.

It will thus be seen that in all of the embodiments of this invention a low draft less dust collector is provided ahead of the high draft loss and high efficiency dust collector, so that the large particles of gas borne solids, which are mostly carbon, will be separated from the gases ahead of the high draft loss dust collector, and can be returned to the furnace for reburning, while the smaller particles, which are mostly ash, will be taken out of the gas by the high draft loss dust collector and can be disposed of in the ash handling system. It will also be appreciated that these large particles are separated from the gases in all of the embodiments with the minimum amount of draft loss and are easily reclaimed for reburning. Thus, the baffle systems and constructions illustrated do an efiicient job of removing the large particles which are to be reclaimed, without the loss of draft or excessive pressure drop, and aid materially in reducing fuel costs without materially increasing the power consumption required to pull the gases through the system.

It will, furthermore, be appreciated that one or more low draft loss dust collectors may be employed in the system, and that such dust collectors may be disposed immediately adjacent the boiler outlet, ahead of the heat exchanger or air heater, or may be disposed behind the heat exchanger so as to remove the particles from the gas after the gas has passed through the heat exchanger. In any event, the large particles are "reclaimed in a simple manner, and a more efficient system is provided.

What is claimed is:

1. Apparatus for separating gas borne particles from gas, including an inlet conduit through which the gas may flow, a hopper disposed below said inlet conduit and having an inlet portion confronting and communicating with said inlet conduit so as to be capable of receiving the particles separated from the gas, an outlet conduit communicating with said inlet conduit above said hopper inlet portion, the longitudinal axes of said inlet conduit and said outlet conduit intersecting at substantially rightangles, a first baiiie element fixed to said inlet conduit at a position adjacent the top of said outlet conduit and extending generally toward the intersection of said axes so as to reduce the area of said inlet conduit, said first baffle element turning gas flowing through said inlet conduit angularly to the direction of the flow of gas through said inlet conduit at an increased velocityso that said gas and gas borne particles will turn through an angle more than ninety degrees in flowing through said inlet conduit and out through said outlet conduit, and a second baffle element fixed to said inlet conduit at a position adjacent the bottom of said outlet conduit and projecting inwardly toward the intersection of said axes, said second baffle rojecting into the path of the turning gas and presenting a surface facing said hopper inlet portion for skimming gas borne particles from the gas prior to the passage of the gas through the outlet con duit, whereby said particles will fall downwardly into said hopper.

2. Apparatus for separating gas borne particles 7 from gas, including aninlet -conduit .through which the gas flows, hopper means disposed :below said inlet conduit and having anainletiportion confronting and communicating with said inlet conduit so as to be capable of receivingparticles separated from the gas, an outlet .conduit communicating with said inlet conduit :above said hopper inlet portion, the longitudinalaxes of said inlet conduit and said outlet conduit intersecting at substantially right angles, a first 'baflle element fixed to said inlet conduit at a .positionadjacent the top of said outlet conduit and extending generally toward the intersection of said axes so as to reduce the area of saidinlet conduit, said first baffie element turning gas flowing through said inlet conduit angularly to the direction of the flow of gas through said inlet conduit at an increased velocity and causing said gas and gas borne particles to make more than aninety degree turn when flowing out through said outlet conduit, additional conduit means connected with said first bafiie element adjacent the inner end thereof and extending from said first baflle element into said hopper means so as to be capable of carrying gas borne particles into-said hopper means, a second bafile element at the upper end of said additional conduit means and spaced inwardly from the inner end of said first baifie element for skimming off gas borne particles and causing the same to flow downwardly through said additional conduit means into said hopper means, and a third bafile elementfixed to said inlet conduit at a position adjacent the bottom of said outlet conduit and projectin inwardly toward the intersection of said axes, said third baffle element projecting into the path of-the turning gas and presenting a surface facing said hopper inlet portion for engaging gas and gas borne particles just prior to the flow of the gas through said outlet conduit so as to skim olf gas borne particles, whereby thesame will fall into said hopper means.

3. Apparatus for separating gas borneparticles from gas, including an inlet conduit through which the gas flows, hopper means disposed below said inlet conduit and having an inlet portion confronting and communicating with said inlet conduit so as to be capable of receiving particles separated from the gas, an outlet conduit communicating with said inlet conduit above said hopper inlet portion, the longitudinal axes of said inlet conduit and said outlet conduit intersecting at substantially right angles, a first baflie element fixed to the wall of said inlet conduit which is opposite the entrance to said outlet conduit, said first bafiie element projecting inwardly and downwardly from a position upwardly spaced from the top of said outlet conduit so as to turn gas flowing through said inlet conduit toward the cut anee of said outlet conduit, a second baflie ele ent fixed to said inlet conduit at a position adj cent the top of said outlet conduit and ex ten ing generallj toward the intersection of said axes so as to reduce the area of said inlet conduit, said second baiiie element turning as flowing through said inlet conduit angularly toward said opposite inlet conduit wall at an increased velocity and causing said gas and gas borne particles to make more than a ninety degree turn when flowing out through said outlet conduit, a

plurality of vertically spaced .bai'lle elements adjacent'to but spaced from said opposite inlet conduit wall anddisposed laterally opposite the entrance to said outlet conduit so that gas borne particles flowing toward said opposite wall will be engaged thereby and will drop downwardly into said hopper means, and a third bafile element fixed to saidinlet conduit at a position adjacent the bottom of said outlet conduit and projecting inwardly toward the intersection of said axes, said third baffie element projecting into the path of theturning gas and presenting a surface facing said hopper inlet portion for engaging gas and gas borne particles just prior to the flow of the gas throughsaid outlet-conduit so as to skim off gas iborne particles, whereby the same will fall intosaid hopper means.

4. Apparatus for separating gas borne particles from gas, including a vertically extending inlet conduit through which the gas flows, hopper means disposed below said inlet conduit and having an inlet portion confronting and communicating with said inlet conduit so as to be capable of receiving particles separated from the gas, a horizontally extending outlet conduit communicating with said inlet conduit above said hopper inlet portion, the longitudinal axes of said inlet conduit and said outlet conduit being substan tially co-planar and intersecting at substantially right angles, a first baifle fixed to said inlet conduit at a position adjacent the top of said outlet conduit and extending generally toward the intersection of said axes, said first baille reducing the area of said inlet conduit so as to provide an orifice through which the gas flows thereby increasing the velocity of the gas and particles flowing past the first baiiie and at the same time deflecting the gas and particles away from the outlet conduit at an angle to the direction of flow of gas through said inlet conduit, so that the gas borne particles will turn through an angle of more than ninety degrees when flowing through said inlet conduit and out through said outlet conduit at an increased velocity which will cause the larger particles to drop into said hopper means but permit the smaller particles to be carried with the gas through the outlet conduit, and a second baiile fixed to said inlet conduit adjacent the bottom of said outlet conduit and projecting inwardly toward the intersection of said axes, said second baflle projecting inwardly into the stream of the turning gas and presenting a surface facing said hopper inlet portion to cause particles to be deflected downwardly into said hopper means.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,048,533 Hoffman Dec. 31, 1912 1,211,235 Robertson Jan. 2, 1917 1,382,100 Lindstrom June 21, 1921 1,562,352 Lundquist Nov. 17, 1925 2,047,568 Lissman July 14;, 1936 2,051,924 Watzke Aug. 25, 1936 2,221,385 Rogers Nov. 12, 1940 2,263,433 Allen Nov. 18, 1941 2,343,895 Flisch Mar. 14, 1944 

